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Thread: RO Water to Tankless Heater (We have a well)

  1. #1
    Join Date
    Oct 2017
    Location
    Fairbury
    Posts
    6

    RO Water to Tankless Heater (We have a well)

    Hey everyone,

    We are in a very rural area, and will be using a well for our water. We're just a 1bbl for now, and testing the waters (pun intended)…

    Here's our situation and what we want:
    - We must use well water to brew with
    - We are going to RO filter the water into a holding tank
    - We are then going to heat it to 165 or so through a tankless water heater (Rennai C199 was our hope) straight into the HLT, allowing us to double batch in one shift by not waiting at all on the HLT to heat


    Our problem is that Rennai said we shouldn't use RO water through their tankless water heaters, as the water will pull metals from the internals of the heater, and eventually the heater will fail. What would you guys suggest? My first thought is a second and smaller holding tank that I can fill with the proper amount of water for each batch, treat it, and then put it through the tankless heater. Then the untreated water in the larger holding tank would still be there to go to the taproom for drinking water and to a hose for cool spotless rinses.

    Thanks in advance!

  2. #2
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,794
    Someone better qualified will be by to advice you on the filtration, soon, we hope. I'm thinking RO might be overkill, and a nano-filter might suit your needs better

    Something to keep in mind RE on-demand heaters: They have very low throughput at any significant delta T. We use three Rinnai C199s to heat our HLT by recirculation. When we heat our 160F castback cooling water to 185F, we can get around 6 gpm from each unit. When directly heating ~50F tap water to 185F, the throughput drops to less than 3 gpm.

    We were told by the sales people we bought these from that we could expect more like 10gpm/unit. That is true--if we're not heating the water. Be sure you can run a batch with around 3-4 gpm if you're drawing straight through the heater.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  3. #3
    Join Date
    Nov 2009
    Location
    Moab, Utah
    Posts
    484

    Water .....

    The Tech guys are correct. You do not want to use ion hungry water in that kind of a machine. R.O. water is in fact very bad for a lot of reasons that are not discussed in real terms near enough. My first question would be is the well water really that bad?/?
    Second thing is Tankless Technology is lame on a good day, no matter what anyone says who is running it.
    The people that attempt to defend it have not understood or dealt with the " finer " points and for sure never looked at the complexity of how they operate or the DIAG. flow charts and electronics. There is no reason to complicate the heating of water in such a way. They are time wasters supreme when they fail.
    Tankless is a cut corner, dirt cheap, attempt to heat water too quickly. Just the facts......
    Those units contain too many moving parts that are made of too much plastic. When running at temps from dead cold inlet and attempting to get foundation or sparge at 170-180F, this is on the wire of design for the top units out there. Its throw away Technology that will fail when you need it most.
    Can they work on a small scale, yes.
    Large process plants of various types will often times have a system in place to treat large quantities of water for cooling towers or other facets of process.
    Steam Boilers can be run on " Softened " water with the correct chemistry added into the feedwater.
    Steam Boilers of the older designs will be running long after many tankless units are dead in the junk yard.
    I would be leaning towards a different way to heat if the water challenges prove too extreme.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    " No Cell Phone Zone."

  4. #4
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,794
    RO water isn't very good for drinking water, either. It tastes absolutely flat with no ions to give it flavor.

    Have you had the well water tested?
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  5. #5
    Join Date
    Feb 2016
    Location
    San Francisco, CA
    Posts
    81
    Don't mean to upset the apple cart, but, have you considered just using a real big HLT? Say, 3x your system size, you'll nearly empty it on those double batch days, but you'll fill it back up again with your heat exchanger when you knock out, with water that should be plenty hot for the HLT's element to get the rest of the way to mash/sparge temp overnight so you can do it all again tomorrow. I'm no hater of tankless heaters, we use one for cleaning/utility water around the brewery, but there's something about having all your brewing liquor right there, ready to go, and available as fast you can pump it; waiting on heaters and filters in the middle of a brewday is the worst.

  6. #6
    Join Date
    Feb 2018
    Location
    Fort Wayne, Indiana
    Posts
    31
    I am on a well too. I am just softening and running it to a 50 micron filter. I am using the same water for cleaning and for Mead.

  7. #7
    Join Date
    Nov 2009
    Location
    Moab, Utah
    Posts
    484

    MERUS Ring

    There is a Device known as the " MERUS Ring " that is said to be successfully implemented at Sapporo.
    It is a Technology that creates a field effect in the water as it passes through the ring.
    They are being used in other large industry as well with documented success.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    " No Cell Phone Zone."

  8. #8
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,794
    Hmm... a passive device that uses no power to "alter the molecular vibrations"? Yeah, that sounds really legit to me.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  9. #9
    Join Date
    Sep 2012
    Posts
    31
    Quote Originally Posted by TGTimm View Post
    Hmm... a passive device that uses no power to "alter the molecular vibrations"? Yeah, that sounds really legit to me.
    It cured my cancer! And freshened my breath! Best of all, it did my tax return, and I got a huge refund!

  10. #10
    Join Date
    Oct 2014
    Location
    Kent, WA
    Posts
    306

    An Alternative opinion

    I'd like to offer an alternative opinion to the collective thinking on an RO system. If you're trying to purify water completely, you usually run at a high recovery rate (the exact rate depends on a lot of factors, but typically 75-90%). But there's nothing that says you have to.

    Commercial systems usually allow you to adjust your recovery rate, so you don't necessarily have to produce extremely low TDS water. Now, if your water is very hard, conventional wisdom says you use a salt-regenerating water softener (which produces a lot of na+ cations in the product water), followed by RO at a relatively high recovery rate. Sodium is rejected very well by TFC membranes, so you can get away with that type of softening. But it can produce pretty pure water, and maybe the TDS is too low to use in metallic piping systems.

    On the other hand, you might be able to use RO by itself (no softening pre-treatment) at a relatively low recovery rate to get your target TDS. If your water is very hard, you may need to inject anti-coagulant to the feed to prevent fouling of the membrane. But the need for chemical injection goes down with the recovery rate. So if your feedwater is, say about 600 mg/l, you can adjust the recovery until the permeate is 200 mg/l, and go from there.

    Depending on the mineral composition of your feedwater, you'll probably still need to add back something to get a particular water profile, but you won't be sending de-ionized water to your brewing system.

    I have one other comment on the "ion hungry" water theory. I've heard people say you can't run ultra high purity water in stainless steel piping, but that's not been my experience. Usually you use PVDF or something similar, but if the stainless tubing is electropolished internally, I've seen this work for years in constant operation. If the water is degassed (no CO2), it's not as aggressive as you'd think. If your TDS is in a more reasonable range, I don't believe you even need electropolished tubing.

    Regards,
    Mike Sharp

  11. #11
    Join Date
    Nov 2010
    Location
    Carmel, IN
    Posts
    29
    I agree that you can get by with using RO in stainless piping, but its not ideal. However with respect to the original question, running raw RO through a tankless heater that likely has copper piping, is going to destroy it.
    WaterEng
    Engineering Consultant

  12. #12
    Join Date
    Feb 2015
    Location
    Dimondale, MI, USA
    Posts
    3
    We are currently running a very similar setup as to what you are proposing and thus far it has been working out great. We have a 3.5bbl system and our tankless hot water heater meets our sparge and cleaning needs. We have well water which we run through an RO system into two large holding tanks. From there I can send it through our tankless or just through the cold lines in the building. Regarding our tankless heater, I did quite a bit of research and landed on the Navien NPE-240. This is a 199,000 BTU/H commercial unit that has two stainless steel heat exchangers as opposed to copper. Max temp is 182F on the unit. Flow rate absolutely drops as you increase in temperature but we run it at 170F with no issue in flow rate. Cheers!


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